Solution for use in testing wells



Patented Mar. 19, 1935 .1

V UNITEDSTATES sermon" For;

PATENT OFFICE usnnv TESTING WELLS I George H. Ennis, Long Beach, Calif.,asslgnor of acne-half to Robert, V. Funk, Long Beach,

No Drawing. Original application February 3,

1930, Serial No. 425,521.

Divided and this appllcatlon January 16, 1931, Serial No. 509,284 1:Claims. .(Cl. -433) My invention relates to a testing solution orcomposition of matter for use in testing an oil well for determining thepoint at which water enters the well; and this application is a divisionof my application entitled Method of testingopen and in some instancesreducing the oil yieldof the well to the extent that the operation ofthe well is impractical; 1

According to present practice, the well is drilled and various casingsare set in place. If it is found that 'water'is leaking into the wellthe point of leakage must be found and the water bearing strata must besealed off. This sealing operation is usually accomplished by extendinga casing down to a. shale or rock stratum below the water bearing strataand cementing the casing thereto. The last casing usually installed in awell is known as the oilstring. The lower end of the oil.

string is extended into the oil. sands and is perforated to allow theoilto enter. The upper end of the oil string is above the surface of theground and is connected to piping for conveying away the oil. Sometimeswater bearing strata islo'cated adjacent the oil sands and a portion ofthe perforated pipe passes therethrough; this allowing the ingress ofwater into the well. When this condition exists, the water bearingstrata must be found andcemented from the wall. J

The foregoing outlines the procedure of install-' ing casing andcementing casing in a well when water leakages are encountered. Thereare, processes at present forlocating theleakage of water into the wellafter the casing strings have been set, and such a process is disclosedin my application entitled Method and apparatus for determining thelocation of water strata in wells, Serial No. 80,160, filed June 9,1926, which issued into also holds back the seepage of water into thewell;

and because of this there will be no leakage" of water into the welluntil after the casings have been set and the rotary mud removed from.the well, so that the hydrostatic head is reduced sufficiently so thatthe pressure against the formation is insuilicient to restrain an inwardflow. At this time if there are any'openings in or around the casingadjacent to arm communication with the water strata the water will startto leak into the well.

It will therefore be seen that ordinarily'the operator of the well hasno way of knowing whether or not there will be water leakages into thewell until after all the casings have been installed, the rotary mudremoved from the well and the hydrostatic head reduced. Many thousandsof dollars are sometimes spent'in installing a casing in a well. andthen when the rotary mud is removed it is found that water still leaksinto the well.

In my copending application Ser. No. 425,521, 7

referred to, I disclose a method whereby the well may be tested forwater leakages before all of thecasings have been set and before therotary mud has been removed from the well, thus enabling the waterleakages to be located and then sealed by either cementing or by theinstallatingof a casing. That invention'further makes it possible totest a well for water leakages before any flow of oil has been started.

In performing that method of determining water leakages in an open holethere have been many difiiculties to overcome and many problems tosolve. v I

In an open hole; that is, a well in which all the casing has not beenset and in which at least a. portion is unprotected by casing, therotary inud is maintained in the hole for a number of reasons, aspointed out above. In order to test the well to locate the water strataa testing solution must be introduced into the well. This testingsolution which is to be used should possess allof the qualities of therotary mud, such as pointed out heretofore, as well as certain qualitieswhich render it suitable for use as a testing solution. It is furtherdesirable that the testing solution have qualities which prevent it fromstratifying and prevent it from being driven into the formations by thehydrostatic head in the well.

My invention provides a testing solution which has the essentialqualities as specified above, which renders the method of testing in anopen hole a success, by preserving the condition of the well during thetesting.

. There are two methods of testing a well for Water leakages. One ofsuch methods is disclosed in my copending applications Ser. No. 425,521and Ser. No. 80,160, both of which have been referred to, and consistsof measuring the electrochemical It is the object of this invention toprovide'atesting solution for use in either'of the aforemen-' r tionedmethods.

In the first mentioned method the testing solution must include amaterial having electrochemical qualities; and I will refer to suchmaterial as an electrolyte. In the second mentioned method the testingsolution must include a material which has electrical resistance orconductivity; and I will refer to such material as resistance material.The electrolyte and the resistance material will be broadly referred toas testing solution.

When atest is made in an open hole- I find it most satisfactory todetermine the weightand glutinous qualities of the rotary mud, and tothen provide the testing solution with the same or nearly the samequalities. The testing solution should be of approximately the samespecific gravity as the rotary mud, in order that the testing solutionwill not fiow from the level at which it is placed.

It is usually desirable to providethe testing solution with glutinouscharacteristics which will prevent Stratification of the substancescomprising the solution and prevent the solution from being driven intothe formations.

In some wells it is desirable'to use both a weight material to give thetesting solution the proper or desired specific gravity and also to usea' glutinous material to give the testing solution the proper or desiredglutinous characteristics. In some wells only the weight material isused in the testing solution and in other wells only the glutinousmaterial is added. The materials used and the amounts'used depend on theconditions in the well, such as the porousness of the formations;

and the character of therotary mud, such as the weight thereof.

I will now describe in detail a number of testing solutionsincorporating the features of my invention.

I will first describe a testing solution adapted for use in the methodof testing a well by measuring the electrochemical action of thesolution in the well such as is fully disclosed in my copendingapplications referred to.

As previously explained, the testing solution used in this method musthave electrochemical qualities, and many different electrolytes aresuitable for use in my invention, and for this reason I willnot attemptto name all of them.

For the electrochemical qualities of the testing solution I may use asolution ,of ammonium chloride, which is strongly ionizable', or anequivalent ionizable material which will retain its electrochemicalqualities in' the presence of the other substances which comprise a partof the electro:

lyte.

I may also use as an electrochemical material a solution which includesammonium sulfate, sodium sulfate, and a colloidalmaterial in a solutionwhich is acid, with sulfuric acid and chromic acid. The colloidalmaterial which I prefer to use if one is used, is alcohol fermentationproduct'of waste molasses after the removal of the alcohol therefrom. Itis known technically as slop. This electrochemically active solution maybe made as follows:

#1 Slop solution (A) Take 10 gallons of concentrated slop. (B)

'Take ygallons of'water andaddgradually gallon of sulfuric acid 66degrees B. (C) Mix A and B and bring to boil, heat for hour, let stand12 hours. Siphon off gallons.

#2 Ammonium sulfate solution Dissolve 300a or ammonium sulfate(fertilizer grade 25% ammonia) in 60 gallons of cold water.

it?Sodium bichromate solution 7 3 parts' (by weight) water, 3 parts (byweight) sodium bichromate, 1 part (by weight) 66 degrees B. sulfuricacid.

6 parts of B solution, making 250 gallons of chemical solution to bedistributed in fluid contents of well by patented dose distributor. Theamount of solution used is 1 gallon of solution approximately to each 48gallons of liquid in the well.

To endow the electrolyte with the necessary weight qualities which inthe testing of some wells may be essential to the electrolyte inorder'that it may support the walls of the hole and hold back the flowof oil, a heavy mineral in finely divided form, is included in theelectrolyte. As a weight material I prefer to use barium sulfate, BaSObut of course other finely divided substances might be used. such forexample as the ferro compounds or oxides. In some instances, asexplained heretofore, I'add to the testing solution a glutinous materialor colloidal mineral such as bentonite clay or other colloidal clays orother inorganic or organic materials capable of providing glutinousqualities. The purpose of the bentonite clay, or the colloidal mineral,is to prevent the electrolyte from being driven by the hydrostatic headinto the formation and to prevent stratification of the dilferentsubstances which compose the electrolyte.

The proportions of the electrochemical material and the weight material.which is preferably barium sulfate, and the glutinous material, orcolloidal mineral, which is'preferably bentonite clay, is used inaccordance with the requirements of the well. In some wells theformation is such that the specific gravity of the electrolyte may bemade lower than in other wells, and likewise in some wells it isdesirable to use more or less colloidal mineral ingredients with thetendency of the electrolyte to penetrate the strata. In some instancesthe colloidal material may be eliminated and in some instances theweight material may be eliminated, but I have found that the mostsatisfactoryelectrolyte is formed when at least a small percentage ofglutinous material is used, due to the fact that the glutinous materialacts as a suspender and prevents the dillerent substances of theelectrolyte from stratifying.

king: an acid electrolyte; bentonite clay; and

tive only and I do not intend to limit myself to the proportions stated.

, Per cent Electrolytic material 85 Glutinous material 10 Weightmaterial If the substrata of the v ell is very porous and the rotary mudquite heavy, a larger proportion of glutinous material may be used toprevent stratification and driving of the testing solution into theformation. If the mud be quite heavy a larger proportion of weightmaterial may be used to give the desired specific gravity.

I will now describe a testing solution adapted for use in the method oftesting a well by measuring the resistance or conductivity of thesolution in the well; such as is described in the Huber pat- "entsreferred to. v

I The testing solution need have no electrolytic 'qualities but musthave qualities of resistance" .or conductivity difierent from that ofthe water in the well to be tested. The water which leaks tinto the wellis either fresh water, or a salt water,

or brine. well has no or very little salt content, the testing solutionmay be salt water or brine, and where it is salt water or brine whichleaks into the well, water having no salt content may be used as atesting solution.

To provide the desired specific gravity I add a weight material, and toprovide the glutinous characteristics I add a glutinous material in thesame manner and according to the conditions in the well, as explainedwith respect to the first described testing solution.

Since both methods of testing a well are fully described in my copendingapplications, and the Huber patents, supra, I will not describe suchprocesses herein. My invention is not limited to use in these twoprocesses, and consists of a new composition of matter as defined in theappended claims.

I claim as my invention:

1. As a new composition of matter, a testing solution for use in testingleakages in wells, including: a large volume of acid electrolyte; and asmall volume of bentonite clay intimately mixed therewith.

2. As a new composition of matter, a testing solution for use intesting. leakages in wells, including the following material inapproximately the percentages given: acid electrolyte, 85%; colloidalmineral, and at least 5% of weight material.

3. As a new composition of matter, a testing fluid for use in testingleakages in wells, including: an acid electrolyte; bentonite clay; andbarium sulfate, said testing fluid being free from rotary mud.

4. As a new composition of matter, a testing fluid for use in testingleakages in wells, includbarium sulfate, said materials being thoroughly'mixed together to form a uniform acid electrolytic body, said testingfluid being free from rotary mud.

,b. As a new composition of matter, a testing Where the water whichleaks into "the,

fluid for use in testing leakages in wells, consisting of an intimatemixture of bentonite clay, barium sulfate, and an acid electrolyte whichis of an even and stable mixture, said testing fluid being free fromrotary mud.

6. As a new composition of matter, a testing fluid for use in testingleakages in wells, consisting of an intimate mixture of bentonite clayand an acid electrolyte which is of an even and stablemixture, saidtesting fluid being free from rotary mud.

7; As a new composition of matter, a testing fluid for use in testingleakages in wells, consisting of an intimate mixture .of a clay havingthe characteristics of bentonite clay, a weight material having thecharacteristics of barium sulfate, and an acid electrolyte which formsan even and stable mixture, said testing fluid being free from rotarymud. v

8. A testing fluid for use in testing leakages in wells comprising anintimate mixture of an acid electrolyte, a weight material having thecharacteristics of barium sulfate and of a colloidal material capable ofholding said weight material in proper suspension, said testing fluidbeing free from rotary mud.

9. An electrolytic testing fluid for use in testing leakages into wellsand which will not flow into the formation nor be dispersed in the fluidin the well, comprising: an acid electrolyte; and bentonite claythoroughly mixed therewith to produce an electrolyte having acidcharacteristics and having glutinous characteristics.

10. An electrolytic testing fluid for use in testing leakages into wellsand which will not flow into the formation nor be dispersed in the fluidin the well, comprising: an acid electrolyte; and a small quantity ofbentonite clay thoroughly mixed therewith to produce an electrolytehaving acid characteristics and having glutinous characteristics.

11. An electrolytic testing fluid for use in testing leakages into wellsand which will not flow into the formation nor be dispersed in the'fluidin the well, comprising: an acid electrolyte solution consisting ofelectrolyte and water; and bentonite clay thoroughly mixed therewith toproduce an electrolyte having acid characteristics .and having glutinouscharacteristics.

12. An electrolytic testing fluid for use in testing leakages into wellsand which will not flow into the formation nor be dispersed in the fluidin the well, comprising: an acid electrolye solution consisting ofelectrolyte and water; and a small quantity of bentonite clay thoroughlymixed therewith to produce an electrolyte having acid characteristicsand having glutinous characteristics.

13. An electrolytic testing fluid for use in testing leakages into wellsand which will not flow into the formation nor be dispersed in the fluidin the well, comprising: an acid electrolyte solution consisting ofelectrolyte which includes sodium bichromate and water; and bentoniteclay thoroughly mixed therewith to produce an electrolyte having acidcharacteristics and having glutinous characteristics.

GEORGE H. ENNIS.

